skyplot.cl

Name

skyplot -- create simlulated sky spectrum and corresponding line list

Usage

skyplot inlines outlines outimage

Parameters

inlines = "wmkonspec$lowd_ir_ohlines.dat": File listing sky emission features (units of Ångstroms) and intensities (in arbitrary units). The default input list is a set of OH sky lines from about 0.8 to 2.3 µm which is suitable for most low-dispersions spectra taken with NIRSPEC.
outlines: Output list of sky emission lines. If none is specified, no list is produced.
outimage: Name of image in which to create simulated night sky spectrum. If none is specified, no image is produced.
wavelength = 10000.: Central wavelength [Angstroms] for the wavelength interval over which to produce the simulated spectrum and line list.
dispersion = 2.077: Dispersion [Angstroms/px] of the resulting spectrum. The default was appropriate for a test observation, and should be changed to suit your data.
fwhm = 5.: Width of sky lines [px]. This controls the FWHM of the emission lines in the simulated spectrum. For purposes of comparing the simulated spectrum to the lines in your data it is best to input the FWHM of skylines in your sky spectra.
ncols = 1024: Number of pixels in spectrum. Generally this should be the same as the number of pixels in your NIRSPEC data.
identify = yes: Determine whether or not to label the emission lines in the resultant spectrum with their wavelengths.
nlines = 50: Number of lines to identify. The nlines strongest emission lines in the spectrum will be labeled.
graphics = "stdgraph": Graphics outimage device for plot of night sky emission lines.

Description

Given a list of sky emission features and their relative intensities, this task will generate a spectrum of these lines over the specified wavelength interval. Optionally, the task will create an image and generate a list of the strongest lines in the spectrum.

The task will generate a simulated sky spectrum, centered on the specified central wavelength, based on the input line list inlines. The spectrum has the number of columns specified by parameter ncols and the specified dispersion. A plot of the spectrum is sent to the graphics device specified by the graphics parameter. If the identify parameter is set true, then the nlines strongest features in the spectrum will be labeled with their wavelengths.

If the outlines parameter is defined, the task will create a list of the nlines strongest features in the spectrum and save them to a file. This file can then by used as input to the identify task to obtain a wavelength solution based on the night sky lines.

If the outimage parameter is defined, the task will store the simulated sky spectrum in the specified image.

Examples

Generate a list and a corresponding hardcopy plot of the 50 strongest OH night sky lines between 1.0 and 1.25 µm, putting the linelist into a file lines1.coo:
```
skyplot wmkonspec$lowd_ir_ohlines.dat lines1.coo \
wavelength=11250. dispersion=2.44 fwhm=5 ncols=1024 \
ident+ nlines=50 graphics=stdplot
```
Here is the resulting plot.

Notes

The default linelist is a modified version of that published by Rousselot et al., 2000, A&A, 354, 1134. This version of the linelist has been modified to (a) exclude all lines with intensity less than 10 and (b) combine all P1/P2 pairs of unresolved lines.